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I am about to re-caulk a 24' carvel planked Van de stadt with Sikaflef 291. She has been out of the water for about two years and some planks have opened up seams of 5-8mm. Do I need to try and introduce some moisture into the planking before caulking or half full the seam?
Thanks,
I was told once by an experienced boatbuilder to cork as normal then launch boat and let the timber swell and push out surplus caulking. Then recover boat and remove surplus.
Seemed reasonably logical.
Strathglass
21-11-01, 23:07
You certainly wont require to introduse some moisture as when you relaunch you will certainly heve to remove surples.
291 is a very good idea
The timbers must be bone dry or I hate be critical but she must have been very badly built in the first place! Assuming it that she wasn't built a buy a house chippy your best bet is not to caulk her immediately but to launch her and let a week's worth of tides flow through her for every year she has been out of the water. Then caulk her before repainting her topsides.
But then I'm a bit old fashioned in these things, there is probably a modern solution and long as it isn't too wet her down with a "Fresh" water
(:-{)>
The 5-8mm are the few worst cases, mostly 2-3mm.
If putting in the tide first how long would you dry out for before caulking?
Thanks
There is no rule of thumb on this. If you have a friendly would scientist he/she could probably calculate the absorb and rate off whatever natural reinforced plastic (wood) your vessel is constructed of and give a definitive answer.
The "classic" answer off course is you will know when you see it! (whatever that means)
The real answer is I don't know having spent my chart would pumping out vessels which had spent too long ashore fight got the feeling for the Formula I have already given you but.
But. But with everything to do with the boat's trial and error, especially error are the controlling factors.
If I was in your shoes I would be tempted to caulk with caulking cotton and white lead then put the technology into play and stray with SEA Water until the corking has stopped being expelled. A note of caution use the water in which she will be moored for the amount of mud/sand/(you won't mention it in polite company) will affect the expansion of the wood .
Beware the new inventions however good they seem in the short term the tried and tested method usually is in the long-term a far better bet. As long as off course you don't want a quick fix!
(:-{)>
It doesnt matter if you use salt or fresh water! Try putting sacks all over the planking, roughly sewn together, then get a pice of hose pipe, to go right round the gunwale/toe rail, make smal holes in the pipe, cnnect to a hose both ends and turn on the water supply, this will soak the sacks and the hull will absorb the water and the planks will then swell, you can then caulk, it is a technique used on hulls which have been out of the water for years in dry climates and extreme cold climates, both dry air! Try it. The salt fresh water thing is a falasy! Spores of rot will only grow between certain levels of dampness, wheter it is salt or fresh water it doesnt matter! They used to sink barges in fresh water, to preserve them when they had no work for them, why do hulls rot most at the waterline, in salt water, think about it! It is now a proven fact!
Fresh water no under no circumstances freshwater will rot would 10 times faster than salt water salt keeps the boat fresh, ever tried to do the experiment of washing some of your bilges out with freshwater and some with salt water? Tthe fresh water once will smell of quicker than the salt water once. Fresh water should only be used for cleaning the salt of the bright work.
(:-{)>
L. F Herreshoff, in either "The Common Sense of Yacht Design" or "The Compleat Cruiser", recommends rinsing the whole of the inside of the boat with fresh water, using a hose, at laying up time, then lighting the coal stove to dry her through again. His point is that it is the tiny crystals of salt which are carried into the boat through the season which attract the damp and which keep her damp and smelly.
I used to have a mortal dread of fresh water, but some years ago I put the above advice into practice. Nearly everyone who comes aboard remarks on how fresh the boat seems, and I have no mildew, etc. problems.
The one thing that will make bilges smell really foul is soapy water; whatever you do, never leave soapy water standing anywhere!
As you say dried salt water will absorb water and keep damp encouraging mildew Etc
Freshwater when the left will go green and stagnant and Snell to high heaven.
For wetting down a conventionally built (carvel or clinker) boat Stanger and water line about will induce rot where a little salt will keep the clanks plimd up.
When you are washing out the interior of a vessel one assumes that and I am certain this is the case with Mirelle
that the pain work and Polish work are sound enough to not let the fresh water penetrate the wood, again when laying up his is a full body skipper who leads a boat with any damp in her. But when washing out the bilges on a regular basis during the season it is easily possible to leave a small puddle of freshwater lurking.
Again the same applies for soap wonderful staff at long as you can guarantee true remove all traces after it has then his work, otherwise the smell is, shall we say "interesting"
(:-{)>
Are you trying to tell me fresh water rots wood and salt water doesnt, just to clarify this point, before going further?
Strewth, Symbol, have you been at the sauce?
I'm clutching at straws a bit here, but a few years ago, in the Tell-Tales section of CB, there was a reference to the wonders of anti-freeze as a timber preservative. I recall that it was an interim announcement from someone who was conducting long term tests, and the editor of the time assured us he would stay on the case. There was a letter or two debunking (I think!) the use of glycolwhat'sitsname, but nothing since. The thrust of the piece was that if one squirts antifreeze onto bare timber inside the hull (possibly exterior, too), it wouldn't require further treatment, or it would stop the timbers drying out ashore. Something like that.
Perhaps, if the editor looks in here, he could check the mag's database, and possibly do a follow up. Always one for a conspiracy theory, when nothing was forthcoming, I conjured up images of Marine Paints R Us PLC nobbling the editor before we realise that all we need for a maintenance free century is a couple of coats of Liebfraumilch!
Have a look at http://boatbuilding.com/content/rot.html.
The timber treatment seems OK, but it's highly toxic, so think long and hard before applying his treatment for rotten toes!
Well, in a way, yes. The higher osmotic pressure of salt water as compared to fresh certainly seems to discourage some types of rot. One does not find many boats with rot in the actual bilge sump. The skeletons of old boats laid aside in creeks seem to rot from the top down, leaving the keel and the checked in timbers like a giant fish bone.
The more concentrated the solution, the better, it would seem (which is why some wooden fishing boats had handfuls of salt chucked into their nether regions and some US built wooden trading ships even had salt stops and salt boxes).
Now, having got that off my chest, I actually agree with your earlier posting; it is the critical level of dampness that does the trick and from that point of view it does not really matter whether the source of damp is salt or fresh. <P ID="edit"><FONT SIZE=-1>Edited by mirelle on Wed Nov 28 17:43:03 2001 (server time).</FONT></P>
Symbol's owner uses voice recognition software when posting; sometimes you need to interpolate.
Polyethylene glycol is the very expensive stuff that the "Vasa" and the "Mary Rose" are preserved with. This leads to occasional speculations that ethylene glycol, ordinary antifreexe, would have some preservative qualities.
There are two serious snags to this; firstly it is toxic but sweet tasting, so children and pets kill themselves by licking it. Secondly it dissolves in water (otherwise why put it in your car radiator!)
Now, then bilge sumps are often full of water, so relative humidity too high! Salt thrown into the nether regions, is a fallacy as I said before, they used to pack salt behind linings in old ships, did that stop them rotting? No it didnt. The ships you see with just the ribs sticking up etc, are one of two things, in the splash zone, ideal rot conditions, or more often, eaten by wood borers etc, weakened then pounded by waves, until they disapear. This is not speculation, but actual fact. I will get hold of the thesis done on this phenomonen and let you know how to get it or get it to you! Think it was done by/for Mystic Seaport museum.
I don't know why but boats kept ashore in a rainy climate tend to rot far quicker than those kept in salt water. those that are kept under cover or ashore in a dry climate do not qualify.
The obvious conclusion is that salt water helps reduce the tendency to rot although no truth is probably that depending on the material, (type of wood) and the rate of rot depends sum woods prefer to be kept wet in fresh something salt and some not wet at all. As far as I know nobody has done a study on woods verses for rot rate verses conditions as experienced by yacht hulls. Or perhaps they have?
(:-{)>
I don't know of any definitive study. The Royal Navy did a great deal of work on the longevity of wooden hulls when it was a matter of National Defence - in 1815 the RN was reduced to its "peace time establishment" and the number of men in the service dropped from over 100,000 to about 15,000. Most ships were laid up. But experience in the 18th century showed that laid up ships rotted - could something be done? The solution was to build ships in India out of teak, sail them home, usually with a "kit of parts" for a sister ship aboard as cargo, then lay them up under a full length roof to keep the rain out. HMS Unicorn (Chatham, 1826) in Dundee is still under her roof and HMS Trincomalee (Bombay 1817) in British West Hartlepool was teak built - both are "Leda" class frigates.
You are certainly right, boats laid ashore and exposed to rain fall apart fast. Boats stored under cover fare much better, and we can conclude that the commonest cause of rot in yachts is rain water. Keep that out and you are probably OK.
Please read what I said again, if the humidity allows (rain etc.) the wood will rot, most boatbuilding timbers. Wood that is kept wet ie. submerged, will not "rot" in fresh or salt. In rainy climates the wood is in ideal rot conditios, if it were salt water rain, impossible I know, but have you seen what happens to wood constantly in salt spray? ie, docks, yes it rots, I'm still looking for the study, I will have to wait until my brother returns from offshore, he has it. Timbers are tested for their durabilty by doing just this, they are put in the ground, ideal rot conditions and then it is seen how long the timber lasts. ie, teak, extremely durable, etc. In the meantime I think I will keep quiet.
Granted wood kept constantly under water does not rot, nor does metal corrode when kept dry metal has not corrode nor wood rot, the constituents which gets metal to corrode is the right humidity with the right amount of oxygen, I wonder whether wood requires oxygen and damp to induce rot like metals oily would tends not to succumb as easily as a un-oiled material. Salt of course will attract damp and may keep would just damp enough to stop rot starting where the lack of salt allows you would drive out just enough to start rotting?
(:-{)>
What about throwing a sackfull of hard wood sawdust in as you put the boat back in .The sawdust gets sucked into the joints as the hull takes up .
Ever though about mud when you have a problem you can certainly slow down the ingress of water through joint's by stirring up the mud .
No I'm not an expert or any thing like but this stuff is common knowledge among the old boy's.
RE prevention of rot I was always told to use Cuprinoil green ,or clear which seap's into the timber helping to preserve it.
I always listen to people that actualy did the work for a living ,they know because they were taught ,and didnt get it from a book.
Mick
Antifreeze was mentioned in issue 23 and again in issue 25 where its preserving properties were mentioned as being used for newly-felled wood being turned for wooden bowls, and as a way of stabilising wood being shown in museums. Pete Greenfield - the then editor, mentioned trying it out on his old dinghy, but I don't think he ever reported back. Conspiracy theorists should probably meet Pete before thinking he could be nobbled. It's quite a bizarre idea!
I was going to use creosote on my boat once. But luckily I asked myself what was the point before I changed my saltwater world into a garden shed.
Having worked with baltic traders for many years, here's what we do...:
During construction frames have a hole drilled in the top, which is filled with salt/brine as often as possible. If the first cargo could be salt, it was much appreciated. Why ? Salt pickles the wood ! Before the age of refrigeration fish & meat could be kept for years when pickled !
Fresh water allows for all sorts of germs & bacteria to grow.
For rot and fungus to appear, a moistore content of more than 25 % is needed, and ventilation is the best way of preventing rot. I am in the process of restoring an old oak on oak working vessel, an have used huge amounts of raw coldpressed linseed oil.
Advantages : It is non toxic, expands 15-20 % when curing (do NOT ad any turps, thinners or the like) and helps keep the moisture content below the 25 %. It allows the wood to breathe and obtain and give of moisture as needed, but at a very slow rate, thereby extending the life of the wood as it doesnt deteriorate as fast....
For wood that doesnt go through the steambox, I have added 1% fungicide.
A moisture content of 25% sounds about right, but! and its a big but, it doesn't matter if the wood is wet with salt water or fresh water, the wood will still rot, look at pilings in old docks in salt water, in the splash zone. The linseed oil sounds a damn good idea, I will use that on some new wood I'm fitting!
Maybe we should rename this subject !
The reason woodpilings rot is more due to the fact that the wood gets wet/gets dry/ gets wet etc.
If the wood had been soaked with linseed oil and tarred, it would last for 200 years or more. In Sweeden they have wooden churches about a 1000 years old !
Untreated wood will absorb more moisture, then dry, and that is what causes the wood to deteriorate, We use beech for keels and under waterline planking, and as long as it is kept submerged,it last nearly as long as oak....but it has also been used as woodpilings under houses and as the groundwaterlevel goes down, so does the houses....
Wood can of course rot anywhere, but go smell a lake and then try the salty Med !
I have been to the Dead Sea, and I can tell You, nothing lives in or near that water !
Wood doesnt rot underwater, the water content of timber will not allow the spores of the fungus that rots the wood live! Around the dead sea it is also very dry, so the wood does not rot, as there is not enough moisture, this is not an easy subject, but that is the simple facts, even the wooden salt carriers used to rot! The timbers under the ground in saturations over 25% dont rot with the fungus, they may well get eaten, by all kinds of worm and gribble etc. but they will not "rot" over or under the moisture barriers. I used to beleive the salt/fresh water rot thing, but since I read a study on this subject I have been forced to change my views. I will try and find the study, I'm sure its on board the boat, but I'm offshore Norway at the moment. I'm not sure I would use beech for anything apart from woodturning, but each to there own. I still like teak, but its so bloody expensive these days and of questionable quality!
ccscott49
if you wish, you may contact me direct on
Morten@milthers.dk
We may be getting a little away from the caulking of the small yacht!
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